Rolls-Royce SMR named as UK's selected technology

Tuesday, 10 June 2025

The UK aims to grow nuclear energy capacity to 24 GW by 2050, with a mix of traditional large-scale power plants and small modular reactors (SMRs). In July 2023, the Great British Nuclear arms-length body, set up to help deliver that extra capacity, began the selection process for which SMR technology to use. There were initially six companies shortlisted, with four shortlisted companies - GE Hitachi, Holtec, Rolls-Royce SMR and Westinghouse - entering negotiations last September. In February, the four SMR vendors were issued with an Invitation to Submit Final Tenders, three of which were submitted in April, with Westinghouse withdrawing.

Great British Nuclear, which has now been renamed Great British Energy - Nuclear as it moves to its delivery phase, today announced that Rolls-Royce SMR has been selected as its preferred partner to develop SMRs, subject to final government approvals and contract signature.

Read more: UK government announces GBP14.2 billion for Sizewell C

It said it is aiming to sign contracts with Rolls-Royce SMR later this year and will form a development company. It will also aim to allocate a site later this year and connect projects to the grid in the mid-2030s. A final investment decision is expected to be taken in 2029.

"This announcement is a defining moment for the UK's energy and industrial future," said Simon Bowen, Chairman of Great British Energy – Nuclear. "By selecting a preferred bidder, we are taking a decisive step toward delivering clean, secure, and sovereign power. This is about more than energy - it's about revitalising British industry, creating thousands of skilled jobs, and building a platform for long-term economic growth."

Rolls-Royce SMR CEO Chris Cholerton said: "This is a day to celebrate a milestone achievement. This success is testament to our incredible team which has developed a world-leading technology and worked tirelessly over the last two years to ensure we could provide a winning tender to GBN.

"As well as delivering affordable, clean energy to support our nation's energy independence - deploying three of our units will drive domestic growth by creating thousands of highly skilled, well-paid jobs and supply chain opportunities. We are the only SMR company with multiple commitments to build projects in Europe, testament to our differentiated design and compelling offer."

The company noted it has already been selected by Czech utility ČEZ to deliver up to 3 GW of electricity in the Czech Republic and that in Sweden Rolls-Royce SMR is in the final two SMRs in their technology selection process. 

The Rolls-Royce SMR is a 470 MWe design based on a small pressurised water reactor. It will provide consistent baseload generation for at least 60 years. 90% of the SMR - measuring about 16 metres by 4 metres - will be built in factory conditions, limiting on-site activity primarily to assembly of pre-fabricated, pre-tested, modules which significantly reduces project risk and has the potential to drastically shorten build schedules.

The Rolls-Royce SMR design is progressing through the final stage of the assessment by the UK nuclear regulators, the only SMR design to have so far reached that stage. The Generic Design Assessment is a three-step process carried out by the Office for Nuclear Regulation (ONR), the Environment Agency (EA) and Natural Resources Wales to assess the safety, security, and environmental protection aspects of a nuclear power plant design that is intended to be deployed in Great Britain. Successful completion of the GDA culminates in the issue of a Design Acceptance Confirmation from the ONR and a Statement of Design Acceptability from the EA.

The selection of Rolls-Royce SMR as the winner of the UK Small Modular Reactor competition was welcomed by the Nuclear Industry Association, with its Chief Executive Tom Greatrex saying: "This is a hugely significant moment for Rolls-Royce SMR and for the British nuclear programme. These SMRs will provide essential energy security and clean power alongside large scale reactors, all the while creating thousands of well-paid, skilled jobs, opportunities for growth right across the country and significant export potential. We look forward to working with Rolls-Royce SMR and all other potential SMR vendors, including those not successful today, on making Britain the best place to build new nuclear anywhere in the world."

The original plan had been for two or three SMR technologies to be selected in the process. And in a statement in the House of Commons Energy Secretary Miliband said that other SMR technology companies may be part of private sector projects in the UK that "may want to come in and build sooner" than the government-backed scheme.

Reaction from Holtec

In response to the announcement on Tuesday, one of the two other shortlisted contenders, Holtec International, said it was disappointed and said its plans for a manufacturing facility in South Yorkshire "will now be scaled back in size and jobs while being delayed in terms of timeframe".

It congratulated Rolls-Royce SMR and said: "Despite the outcome from this competition, Holtec remains resolute in its belief that Holtec’s SMR-300 is among the most advanced, safe, and deployable reactor designs in the world. Our participation in the tender has further reinforced the global interest in our technology, and we are grateful for the opportunity to showcase our capabilities."

"Looking ahead, Holtec is intensifying its focus on partnerships with private-sector clients in the United Kingdom that can move at pace and international stakeholders who are seeking proven, scalable SMR solutions," its statement added.

Large plant plans

The selection of Rolls-Royce SMR came as Chancellor Rachel Reeves announced the UK government will make a GBP14.2 billion (USD19.2 billion) investment to build Sizewell C nuclear plant in Suffolk as part of its Spending Review. The EDF-led plan is for Sizewell C to feature two EPRs. It would be a similar design to the two-unit plant being built at Hinkley Point C in Somerset, with the aim of building it more quickly and at lower cost as a result of the experience gained from what is the first new nuclear construction project in the UK for about three decades.

Miliband told members of parliament that Wylfa, in North Wales, was being considered by Great British Energy - Nuclear for potential future nuclear use, for either a further gigawatt-scale plant, or as a site for multiple SMRs.

What is an SMR?

Small modular reactors - also known as SMRs - are smaller nuclear power plants and are intended to be designed so that their parts can be factory-produced and assembled on site in a modular way allowing costs to fall as increasing numbers of the same SMR design are built.

The widely-accepted definition of an SMR is that it is a nuclear power reactor which has an output level of up to 300 MWe, which is about one-third of the power generated by a traditional-sized nuclear power plant unit. Each SMR could power about 600,000 homes, probably for 60-80 years.

There are more than 70 different SMR designs in development, with Russia, China and Argentina leading the way in terms of constructing them so far with many other countries having hopes and plans for fleets of SMRs during the 2030s.